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排序方式: 共有753条查询结果,搜索用时 31 毫秒
91.
Iwao Ishino Masayuki Hikita Yasuo Suzuoki Teruyoshi Mizutani Masayuki Ieda 《Electrical Engineering in Japan》1992,112(7):1-9
The electrical breakdown and electrical conduction of ethylene copolymers have been studied. The electric strength of ethylene copolymers containing an optimum content of halogen moieties such as bromophenyl and fluoroethylene groups was found to be higher than that of LDPE over the wide temperature range from ?196°C to 90°C. Also, conduction currents in the copolymers were suppressed at high electric fields. X-ray-induced thermally stimulated currents (TSC) revealed that halogen comonomers act as carrier traps with a depth of about 0.4 eV. Consequently, the introduction of comonomer-containing halogen groups into polyethylene suppresses electron acceleration as a result of an increase in trapping and scattering of conduction electrons. This leads to an increase in electric strength which is determined by the electron avalanche breakdown. 相似文献
92.
In the previous papers (Hikita and Ishimi,1976b; 1978, Hikita et al., 1979), the results of theoretical analysis of the mass transfer rate in laminar gas streams in wetted-wall columns have been reported. The similarity of the forms of the basic differential equations for mass and heat transfer makes it possible to apply the results of the mass transfer analysis to the heat transfer analysis. The present study was undertaken to confirm the above analogy between mass and heat transfer experimentally, and to investigate the effect of the gas and liquid flow rates on the heat transfer rate in laminar gas streams in wetted-wall columns. 相似文献
93.
Oleyl and elaidyl alcohol have been stereospecifically hydroxylated by cold, dilute alkaline potassium permanganate toerythro- andthreo-9,10-dihydroxyoctadecanol, respectively, in 40–80% yields in a water-methylene chloride heterogeneous system. Phase transfer agents (PTA) were used to transport permanganate ion from the aqueous to the organic phase. In the absence of PTA, hydroxylation did not take place. Periodic acid cleavage of epoxides in a water-methylene chloride system was studied in the absence and presence of PTA. At slow stirring rates PTA exert a rate accelerating effect in cleaving certain epoxides to aldehydes but with vigorous stirring use of PTA has only a marginal advantage. 相似文献
94.
Several quaternary ammonium and phosphonium halides have been shown to be useful phase transfer agents (PTA) for the efficient transport of permanganate, periodate, and cyanate ions from aqueous to organic phases (benzene and/or methylene chloride). Chemical and spectral methods of analysis were used to measure ion transfer quantitatively and to assess the relative efficiency of PTA. 相似文献
95.
Hideki Fujiwara Toko Kimura Masafumi Segi Tomoyuki Nakatuka Hiroya Nakamura 《Polymer Bulletin》1992,28(2):189-196
Summary Mechanochemical block copolymerization in heterogeneous systems of the solid poly(vinyl chloride)-styrene-sodium dodecyl sulfate
aqueous solutions has been studied by ultrasonic irradiation at 65 °C. The block copolymerization of styrene was initiated
by free radicals produced from the poly(vinyl chloride) particles by ultrasonic waves. The initial rate of the block copolymerization
Rp was given by Rp α [Styrene] [Sodium dodecyl sulfate]1/2. Both copolymer and homopolymer were obtained. For example, when 2.506 g of the poly(vinyl chloride) particles, 24.23 g of
styrene, and 54.00 g of sodium dodecyl sulfate aqueous solution (0.500 wt%) were added in the reaction system, the weight
proportions of the block copolymer and polystyrene after 60 min were approximately 50 and 20%. 相似文献
96.
A simple and practical method for minimizing non-linear image contrast in spherical aberration-corrected (C(S)-corrected) high-resolution transmission electron microscopy is presented. The effectiveness of the method is considered from the viewpoints of theoretical formulations and image simulations including second-order imaging effects. The method is one of the advantages of C(S)-correction and applied to high-resolution images down to 0.1 nm. The dynamical diffraction effect is carefully evaluated, which shows that the phase deviation of diffracted waves from pi/2 violates the present method in thicker crystals over approximately 10 nm. 相似文献
97.
Hikita Mitsutaka Kinoshita Yasuaki Kojima Hiroomi Tabuchi Toyoji 《Electronics letters》1980,16(12):446-447
A low-loss narrow band (below 3%) resonant filter has been achieved using twin-turn reflectors and a surface shear wave mode on 36° YX LiTaO3 substrate. 相似文献
98.
Tomoyuki Adachi Naoki Wakiya Naonori Sakamoto Osamu Sakurai Kazuo Shinozaki Hisao Suzuki 《Journal of the American Ceramic Society》2009,92(S1):S177-S180
Fe3 O4 –BaTiO3 composite particles were successfully prepared by ultrasonic spray pyrolysis. A mixture of iron(III) nitrate, barium acetate and titanium tetrachloride aqueous solution were atomized into the mist, and the mist was dried and pyrolyzed in N2 (90%) and H2 (10%) atmosphere. Fe3 O4 –BaTiO3 composite particle was obtained between 900° and 950°C while the coexistence of FeO was detected at 1000°C. Transmission electron microscope observation revealed that the composite particle is consisted of nanocrystalline having primary particle size of 35 nm. Lattice parameter of the Fe3 O4 –BaTiO3 nanocomposite particle was 0.8404 nm that is larger than that of pure Fe3 O4 . Coercivity of the nanocomposite particle (390 Oe) was much larger than that of pure Fe3 O4 (140 Oe). These results suggest that slight diffusion of Ba into Fe3 O4 occurred. 相似文献
99.
Akio Ueda Dai Kato Tomoyuki Kamata Hiroshi Uetsuka Shigeru Hirono Osamu Niwa 《Carbon》2009,47(8):1943-7599
We fabricated electrochemically stable fluorinated nano-carbon film that had an sp2 and sp3 hybrid nanocrystalline structure formed using the electron cyclotron resonance (ECR) sputtering method. This fluorinated ECR (F-ECR) nano-carbon film prepared with a short CF4 plasma treatment has a high fluorine content (F/C:0.20) and a low oxygen content (O/C:0.02) on its surface and retains its original morphology. This F-ECR nano-carbon is capable of a lower capacitance current, and a wider potential window than untreated ECR nano-carbon. The electron transfer rates at an F-ECR electrode are as high as those of untreated carbons for , whereas they are much slower than those of untreated ECR nano-carbon for Fe2+/3+ and owing to its selective sp2 fluorination. These slow electron transfer rates for Fe2+/3+ and are maintained during potential cycles due to its robust nanocrystalline structure. In contrast, these slow electron transfer rates were easily recovered for fluorinated glassy carbon under same condition. Furthermore, a smaller fluorination effect was observed for polycrystalline boron-doped diamond owing to the low reactivity of its sp3 bonds. Our ECR nano-carbon film is suitable for the effective fabrication of a fluorinated surface while maintaining a relatively active electrochemical interface and excellent stability. 相似文献
100.
To improve the cathodic performance of olivine-type LiMnPO4, we investigated the optimal annealing conditions for a composite of carbon with cation doping. Nanocrystalline and the cation-doped LiMn1−xMxPO4 (M = Ti, Mg, Zr and x = 0, 0.01, 0.05 and 0.10) was synthesized in aqueous solution using a planetary ball mill. The synthesis was performed at the fairly low temperature of 350 °C to limit particle size. The obtained samples except for the Zr doped one consisted of uniform and nano-sized particles. The performance of LiMnPO4 was much improved by an annealing treatment between 500 and 550 °C with carbon in an inert atmosphere. A small amount of metal-rich phosphide (Mn2P) was detected in the sample annealed at 900 °C. In addition, 1 at.% Mg doping for Fe enhanced the rate capability in our doped samples. The discharge capacity of LiMn0.99Mg0.01PO4/C was 146 mAh/g at 0.1 mA/cm2 and 125 mAh/g even at 2.0 mA/cm2. 相似文献